Pressure is an important function supporting respiration. A pressure gradient is required to generate respiration flow. In spontaneous respiration, inspiratory flow is achieved by creating a sub-atmospheric pressure in the alveoli by increasing the volume of the thoracic cavity under the action of the inspiratory muscles. During expiration, the intra-alveolar pressure becomes slightly higher than atmospheric pressure and gas flow to the mouth results. 

Airway pressure in humans can recorded through the use of pressure transducers inserted into the throat and connected to our fully isolated and human approved blood pressure amplifiers, a PowerLab data acquisition unit and LabChart analysis software.